KR100547544B1 - Magnetic disk device - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention provides a magnetic disk device capable of achieving flattening of impedance of a transmission line by achieving an improvement in electrical characteristics due to a reduction in transmission loss in a transmission line and an improvement in vibration characteristic by a reduction in rigidity of a head peripheral wiring portion. to provide. To this end, in the magnetic disk apparatus, the transmission line 21e mounted on the suspension 19 is composed of a recording side line 21W made up of a pair of conductors and a reproduction side line 21R made up of a pair of conductors. The lower conductor 34 is provided in the lower layer of the conductor of the line 21W and the regeneration-side line 21R with an insulating layer 33 interposed therebetween, and the lower conductor 34 is formed of copper or copper having a thickness of 5 μm. It is formed of a copper alloy as a main component, the insulating layer 33 is formed of a polyimide resin having a thickness of 5 to 10 µm, and the lower conductor 34 is electrically at ground potential.

Magnetic recording media, magnetic heads, suspensions, preamplifiers, stainless layers

Description

Magnetic Disk Device {MAGNETIC DISC APPARATUS}

1 is a block diagram showing a magnetic disk device according to one embodiment of the present invention;

Fig. 2 is a plan view showing the arrangement of transmission lines on the arm suspension in the magnetic disk device of one embodiment of the present invention.

3A and 3B are cross-sectional views showing the structure (three-layer structure) of the transmission line on the suspension in the magnetic disk device of one embodiment of the present invention.

4A and 4B are cross-sectional views showing the structure (four-layer structure) of the transmission line on the suspension in the magnetic disk device of one embodiment of the present invention.

5A and 5B are cross-sectional views showing the structure (five-layer structure) of the transmission line on the suspension in the magnetic disk device of one embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the structure of the HGA of the example of FIG. 3 in the magnetic disk device of one embodiment of the present invention; FIG.

FIG. 7 is an explanatory diagram showing the structure of the HGA of the example of FIGS. 4 and 5 in the magnetic disk device of one embodiment of the present invention; FIG.

Fig. 8 is a characteristic diagram showing a power change (film thickness of polyimide resin = 5 μm) with respect to the film thickness of the lower conductor in the magnetic disk device of one embodiment of the present invention.

Fig. 9 is a characteristic diagram showing a power change (film thickness of polyimide resin = 10 μm) with respect to the film thickness of the lower conductor in the magnetic disk device of one embodiment of the present invention.

Fig. 10 is a characteristic diagram showing a power change (film thickness of polyimide resin = 18 μm) with respect to the film thickness of the lower conductor in the magnetic disk device of one embodiment of the present invention.

Fig. 11 is a characteristic diagram showing the relationship between the conductivity of the lower conductor and the film thickness (film thickness of polyimide resin = 5 μm) in the magnetic disk device of one embodiment of the present invention.

Fig. 12 is a characteristic diagram showing the relationship between the conductivity of the lower conductor and the film thickness (film thickness of polyimide resin = 10 m) in the magnetic disk device of one embodiment of the present invention.

Fig. 13 is a characteristic diagram showing the relationship between the conductivity of the lower conductor and the film thickness (film thickness of polyimide resin = 18 μm) in the magnetic disk device of one embodiment of the present invention.

FIG. 14 is an explanatory diagram showing a state of induced current generated in a lower conductor when a high frequency current flows through a transmission conductor of a transmission line in the magnetic disk device of one embodiment of the present invention; FIG.

Fig. 15 is a characteristic diagram showing the relationship between the minimum power consumption and the conductivity of the lower conductor in the magnetic disk device of one embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

10: HDA

13: magnetic recording medium

14: magnetic head

14 W: Coil terminal for recording head

14R: output terminal of the playhead

15: carriage part

16: FPC

18: arm

19: Suspension

20: preamplifier

20W: recording amplifier

20R: Regenerative Amplifier

21, 21a, 21b, 21c, 21d, 21e, 21f: transmission line

21W: Record side track

21R: Regeneration Line

30: recording side conductor

31: reproducing side conductor

32: cover

33: insulation layer

34: lower conductor

35: stainless layer

36: insulation layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly, to a technique that is mounted on a suspension and is effective for applying to a transmission line structure for transmitting a recording / reproducing signal between a magnetic head.

According to the inventors' consideration, the following techniques can be considered regarding the structure of the transmission line of the magnetic disk device.

For example, in a magnetic disk device, in order to record a large amount of data in a limited space and to record and reproduce a large amount of data in a short time, a high recording density technique and a high speed transfer technique of data, that is, high frequency recording and reproducing frequencies It is required.

Such a magnetic disk apparatus has a structure in which a transmission line for transmitting a recording / reproducing signal to and from a magnetic head is printed and mounted on the suspension. The transmission line is composed of a recording side line composed of a pair of conductors and a reproduction side line composed of a pair of conductors. The lower conductor is provided in the lower layer of the conductor of the recording side line and the reproduction side line with an insulating layer interposed therebetween.

In such a transmission line, conventionally, the conductors of the recording side line and the reproduction side line are formed with a thickness of about 15 μm of copper, and the lower conductor is formed with a thickness of about 25 μm of stainless, and the insulating layer is made of polyimide resin. It is formed to a thickness of about 10㎛.

For example, Patent Document 1 (Japanese Patent Laid-Open No. 2002-237016) adheres closely to a plate member having a higher thermal conductivity than stainless steel, which is a material of a suspension, on the back surface of a flexible printed circuit (FPC) constituting a transmission line. This structure has a structure mounted on the suspension. Copper etc. can be used for this board member other than aluminum, The thickness has an upper limit of about 500 micrometers.

By the way, as a result of the present inventor's examination of the structure of the transmission line of the magnetic disk device as described above, the following points became clear.

For example, in the conventional transmission line as described above, since the lower conductor of the lower layer of the conductor of the recording side line and the reproduction side line is formed of stainless, there is a problem such as a large transfer loss.

In addition, in the magnetic disk apparatus, it is necessary to lower the rigidity of the wiring portion around the head to increase the followability of the magnetic head to the surface shape of the magnetic recording medium. However, when the upper limit of the thickness of the plate member by copper is set to about 500 micrometers like the said patent document 1 (Unexamined-Japanese-Patent No. 2002-237016), since the lower conductor by this plate member is thick, rigidity is high, It is difficult to apply to the wiring portion around the head. In the case of application, it is necessary to remove the lower conductor and install the wiring by only one layer. For this reason, not only does impedance control not be possible, but also there exists a problem of being easy to be influenced by external noise.

In addition, in the conventional transmission line as described above, in order to apply to the wiring portion around the head, if the lower conductor made of stainless is made thin, the loss leads to an increase. This phenomenon is mentioned later.

Therefore, in the conventional transmission line as described above and in the technique such as Patent Document 1 (Japanese Patent Laid-Open No. 2002-237016), it is difficult to achieve both the reduction of the transmission loss of the transmission line and the reduction of the rigidity of the head peripheral wiring part. A solution is required.

Accordingly, an object of the present invention is to realize the flattening of the impedance of the transmission line by making the improvement of the electrical characteristic by the reduction of the transmission loss in the transmission line and the improvement of the vibration characteristic by the reduction of the rigidity of the head peripheral wiring part. A magnetic disk device is provided.

The present invention has a magnetic head for recording and reproducing information with respect to a magnetic recording medium, a transmission line for transmitting a recording and reproduction signal between the magnetic head, and a suspension for mounting the transmission line. Applied to a magnetic disk device, the transmission line structure on the suspension has the following characteristics.

(1) The transmission line mounted on the suspension is composed of a recording side line consisting of a pair of conductors and a reproduction side line consisting of a pair of conductors, with an insulating layer interposed between the recording side line and the conductor of the reproduction side line. The lower conductor is provided, and the lower conductor is formed of copper or copper alloy whose main component is about 5 µm in thickness. The insulating layer is formed of a polyimide resin having a thickness of about 5 to 10 µm, and the lower conductor is electrically at ground potential.

(2) In the above (1), the lower layer of the lower conductor is provided with a stainless layer, which is formed as a flexure and incorporated with the suspension.

(3) In the above (1), the lower layer of the lower conductor is provided with a stainless layer interposed therebetween, and the stainless layer is formed as a flexure and is integrated with the suspension.

<Example>

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in the whole figure for demonstrating an Example, the same code | symbol is attached | subjected to the member which has the same function, and the repeated description is abbreviate | omitted.

First, with reference to FIG. 1, an example of the structure of the magnetic disk device of one embodiment of the present invention will be described. 1 shows a configuration diagram of a magnetic disk device.

The magnetic disk apparatus of this embodiment is constituted of, for example, an HDA (head disk assembly) 10, a recording / playback control circuit 11 and the like.

The HDA 10 is composed of a spindle portion 12 on which a magnetic recording medium 13 is stacked, and a carriage portion 15 mounted with a magnetic head 14 or the like for recording and reproducing information on the magnetic recording medium 13. It is a structure surrounded by an aluminum base and a cover.

The carriage portion 15 is provided at the tip of the VCM (voice coil motor) 17, the arm 18, and the arm 18 for seeking and positioning the magnetic head 14 on the magnetic recording medium 13. The attached suspension 19, the magnetic head 14 attached to the front end of the suspension 19, an FPC (flexible patterned cable) 16 for transmitting a recording / reproducing signal, and an R mounted on the FPC 16. A preamplifier 20 in the / W IC and a transmission line 21 for transmitting a recording and reproducing signal between the preamplifier 20 and the magnetic head 14 are constituted.

There is a recording / playback control circuit 11 between the HDA 10 and the external device. This recording / reproduction control circuit 11 may be provided inside the HDA 10. The recording / reproduction control circuit 11 is equipped with a signal processing LSI 22 and an HDD (hard disk drive) controller 23. By connecting the connector 25-1 on the HDA 10 side and the connector 25-2 on the recording / reproduction control circuit 11 side, the preamplifier 20 and the signal processing LSI 22 are connected. The external device 24 is connected to the external device via the external interface 24 of the recording / playback control circuit 11.

Next, with reference to FIG. 2, an example of the arrangement of the transmission lines on the arm suspension in the magnetic disk device of this embodiment will be described. 2 shows a plan view of the arrangement of the transmission lines on the arm suspension.

As shown in FIG. 2, the transmission line 21 from the preamplifier 20 to the magnetic head 14 is arranged along the width of the arm 18, and is formed on the suspension 19 by printing. The magnetic head 14 provided with the recording head coil terminal 14W, the reproducing head output terminal 14R, and the like are connected to the front end of the printed transmission line 21. The other end of the transmission line 21 is connected with a preamplifier 20 composed of a recording amplifier 20W and a reproduction amplifier 20R.

The transmission line 21 is composed of a bottle line part where the recording side line 21W and the reproduction side line 21R are juxtaposed, and a separate separating part, and the bottle line part on the printed suspension 19 is formed. The positional relationship and structure of the recording side line 21W and the reproduction side line 21R are as shown in Figs.

Here, the recording operation and the reproduction operation of the information in the magnetic disk device will be described.

In general, recording of information is performed as follows. First, information input from the host apparatus is converted into pattern data suitable for magnetic recording reproduction. Next, the polarity inversion of the write current is associated with the pattern data '1', and the inversion is not associated with the data '0'. The write current in which the polarity inversion current is associated with the pattern data is output from the write amplifier 20W of the preamplifier 20 to the write side line 21W. This writing current reaches the recording head coil terminal 14W of the magnetic head 14 via the recording-side line 21W.

Then, it is energized from the recording head coil terminal 14W to the recording magnetic field generating coil inside the magnetic head 14 to generate a recording magnetic field having the direction of the magnetic field corresponding to the polarity of the current. The magnetic recording medium 13 records the inversion of the current corresponding to the data pattern '1', that is, the magnetization inversion, and the inversion of the current, that is, the magnetization inversion, is recorded in the data pattern '0'.

On the other hand, in the reproduction of the recording information, the reproducing head (MR head) in the magnetic head 14 senses the magnetization direction of the magnetic recording medium 13 and inputs it to the preamplifier 20 as a change in voltage. In this preamplifier 20, the reproduction information amplified by the reproduction amplifier 20R is sent to the channel LSI to decode the data pattern, thereby reproducing the recording information.

Next, an example of the structure of the transmission line on a suspension is demonstrated using FIGS. 3 to 5 show cross-sectional views of the structure of the transmission line on the suspension, respectively, Fig. 3 is a three-layer structure, Fig. 4 is a four-layer structure, Fig. 5 is an example of a five-layer structure, and Figs. Each of (a) of 5 is an example when there is a cover, and each of (b) of FIGS. 3 to 5 is an example of no cover. 6 and 7 show explanatory views of the structure of the HGA (head gimbal assembly), FIG. 6 shows an example of FIG. 3 and FIG. 7 shows an example of FIGS. 4 and 5, respectively.

In the transmission line 21a on the suspension shown in Fig. 3A, the recording side line 21W and the reproduction side line 21R are arranged at predetermined intervals, respectively, a pair of recording side conductors 30, It consists of a pair of regenerative side conductors 31. These recording-side conductors 30 and reproduction-side conductors 31 are arranged on the insulating layer 33 stacked on the lower conductor 34, and are formed in a print covered structure. In addition, as shown in Fig. 3B, the transmission line 21b without the cover 32 can be used.

In the transmission lines 21a and 21b, in particular, the lower conductor 34 provided with the insulating layer 33 interposed between the recording side conductor 30 and the reproduction side conductor 31 has a thickness of about 5 m. It is formed from the copper or copper alloy which has copper as a main component. The lower conductor 34 is electrically at ground potential. The insulating layer 33 is made of polyimide resin having a thickness of about 5 to 10 µm. The suspension 19 is made of stainless, and the cover 32 is formed of polyimide resin or the like, respectively.

Thus, in the case of the transmission line 21a, 21b of the three-layer structure which consists of the recording side conductor 30, the reproduction side conductor 31, the insulating layer 33, and the lower conductor 34, it is shown in FIG. As described above, one end of the arm 18 and one end (opposite to the magnetic head) of the suspension 19 are joined, and the transmission lines 21a and 21b are formed on the joined arm 18 and the suspension 19. The structure is mounted. In the case of the mounting structure of the transmission lines 21a and 21b, since the transmission lines 21a and 21b are mounted on the suspension 19 by, for example, adhesive, the mounting variations to the suspension 19 are changed. This may happen. Therefore, the structure shown in FIG. 4 can be considered.

In the transmission line 21c on the suspension 19 shown in FIG. 4A, in addition to the structure of FIG. 3, the stainless layer 35 is provided below the lower conductor 34. In the case of the transmission line 21c of this four-layer structure, as shown in FIG. 7, the stainless layer 35 is formed as a flexure and is integrated with the suspension 19. As shown in FIG. Also in this structure, it is also possible to set it as the transmission line 21d without the cover 32 like FIG.4 (b).

The formation of the transmission lines 21c and 21d is, for example, on the lower conductor 34, the insulating layer 33, and the recording side conductor on the stainless layer 35 having the size of the entire surface of the transmission line 21c. 30, the regenerated conductor 31, and the cover 32 (the transmission line 21d has no cover) in the order of printing, and then cut and remove portions other than the flexure of the stainless layer 35. It can form by doing.

In the case of the mounting structure of the transmission lines 21c and 21d, the mounting variation can be reduced by mounting the stainless layer 35 and the suspension 19 by, for example, point welding. Therefore, it is strong by point welding and can be mounted with low fluctuations. In addition, since the suspension 19, the welding point, the stainless layer 35, and the lower conductor 34 can be made common to the ground, it is effective in noise reduction at low frequencies. When low frequency noise is mixed in this structure, the structure shown in FIG. 5 may be used.

The transmission line 21e on the suspension 19 shown in FIG. 5 (a) has an insulating layer 36 formed of polyimide resin under the lower conductor 34, in addition to the structure of FIG. On the other hand, the stainless layer 35 is provided. Also in this transmission line 21e having a five-layer structure, as shown in Fig. 4, the stainless layer 35 is formed as a flexure and incorporated with the suspension 19, as shown in Fig. 7. Also in this structure, it is also possible to set it as the transmission line 21f without the cover 32 like FIG.5 (b). Also in the formation of these transmission lines 21e and 21f, it can form similarly to FIG.

In the case of the mounting structure of the transmission lines 21e and 21f, the insulating layer 36 is sandwiched under the lower conductor 34, a stainless layer 35 is provided below the insulating layer 36, and the stainless layer 35 ) And the suspension 19 are mounted by, for example, point welding, so that the lower conductor 34 can be separated from the ground. Therefore, it is strong by point welding and can be mounted with low fluctuations. In addition, since the lower conductor 34 can be separated from the ground, mixing of low frequency noise can be prevented.

8-10, an example of the result of having simulated the film thickness dependency of power consumption when copper or stainless steel is used for the lower conductor of a transmission line is demonstrated. 8 to 10 show characteristics of power variation with respect to the film thickness of the lower conductor, wherein the film thickness of the polyimide resin of the insulating layer is 5 μm, FIG. 8 is 10 μm, and FIG. 10 is 18. It is an example of micrometer.

As shown in FIG. 8, the film thickness of the polyimide resin of the insulating layer 33 is an example of 5 micrometers, and copper (conductivity (sigma) = 5.8E + 07 (= 5.8x10 <^7> ) is attached to the lower conductor 34. As shown in FIG. (S / m)), the power is about 120W at the film thickness of about 0.5 µm, but is reduced to about 35W at about 2µm, to about 30W at about 5µm, and 30W at the thickness of more than that. It becomes almost constant. On the other hand, when stainless steel (conductivity σ = 1.1E + 06 (1.1 × 10 ⁶ [S / m]) is used for the lower conductor 34, on the contrary, when the film thickness is about 0.5 μm, the power is about 30 W. The thickness increases to about 100W at about 5 µm, to about 150W at about 5 µm, to about 140W at about 10 µm, and to about 110W at about 20 µm. It can be seen that the electric power can be reduced even if it is higher than the degree, and when the stainless layer is thin, the electric power becomes small, but it cannot be used as a transmission line.

FIG. 9 shows an example in which the thickness of the polyimide resin of the insulating layer 33 is 10 占 퐉. However, in this example, the thickness of the polyimide resin in the lower conductor 34 is about 2 占 퐉 or more when copper is used. It can be seen that the power is reduced to about 25W, so that the power can be further reduced compared to the example of FIG.

FIG. 10 shows an example in which the thickness of the polyimide resin of the insulating layer 33 is 18 µm. In this example, when copper is used for the lower conductor 34, the power is further increased to about 10 W when the thickness is about 2 µm or more. It can be seen that it can decrease.

Thus, when copper is used instead of stainless for the lower conductor 34, it turns out that power consumption can be reduced even if thickness is made thin. This leads to a reduction in transmission loss of the transmission line.

Next, an example of the result of simulating the relationship between the electrical conductivity and the film thickness at which the power consumption of the lower conductor is minimized when copper or stainless steel is used as the lower conductor of the transmission line using FIGS. 11 to 13 is shown. Explain. 11 to 13 show characteristics of the relationship between the conductivity of the lower conductor and the film thickness, respectively. The film thickness of the polyimide resin of the insulating layer is 5 μm in FIG. 11, 10 μm in FIG. 12, and FIG. 13 is 18. It is an example of micrometer.

As shown in FIG. 11, in the example where the film thickness of the polyimide resin of the insulating layer 33 is 5 micrometers, the lower conductor 34 used copper of electrical conductivity (sigma) = 5.8E + 07 [S / m]. In this case, the lower limit of the film thickness at which the power consumption of the lower conductor 34 is minimum is about 2 µm, and the upper limit is about 12 µm. The method for determining the lower limit and the upper limit of the film thickness will be described later with reference to FIG. 14. On the other hand, in the case where stainless steel having a conductivity σ = 1.1E + 06 [S / m] is used for the lower conductor 34, the lower limit and the upper limit of the film thickness at which the power consumption of the lower conductor 34 is minimum are 31. It is about micrometer. Thereby, when copper is used compared with stainless, it turns out that power consumption can be minimized by making film thickness into about 2-12 micrometers.

Although FIG. 12 is an example in which the thickness of the polyimide resin of the insulating layer 33 is 10 micrometers, and FIG. 13 is an example in which 18 micrometers is used, also in these examples, when copper is used compared with the case where stainless steel is used for the lower conductor 34, It can be seen that power consumption can be minimized by setting the film thickness to about 2 to 15 µm.

Next, with reference to FIG. 14, an example of the determination method of the minimum and upper limit of the film thickness at which the power consumption of a lower conductor becomes minimum is demonstrated. 14 is an explanatory diagram of an induced current state generated in a lower conductor when a high frequency current flows through a transmission conductor of a transmission line.

In the simulation shown in FIG. 14, a current of 1 GHz (differential current: for example, left) is transmitted to a transmission conductor of a pair of recording-side conductors 30 and a pair of recording-side conductors 30 and a pair of reproduction-side conductors 31. The conductor is in the direction from the inside to the front, and the right conductor is the direction from the front to the inside). The lower conductor 34 shows the conductivity σ = 5.8E + 07 [S / m], that is, copper. . The same applies to the transmission conductors of the pair of reproduction-side conductors 31.

In Fig. 14, when a high-frequency current of 1 GHz flows through a transmission conductor such as a pair of recording-side conductors 30, the current flows concentrated on the surface portion (Part A). When a current flows through this transmission conductor, an induced current flows through the lower conductor 34 facing the insulating layer 33. The flow direction is the direction opposite to the electric current which flows through a transmission conductor. The distribution of induced currents is larger for the portion closer to the transmission conductor.

FIG. 14 shows the case where the thickness of the lower conductor 34 is thick (10 mu m). As shown in FIG. 14, when the lower conductor 34 is thick, the induction current flows concentrated in a portion (part B) of the lower conductor 34 close to the transmission conductor, and is lower than the portion in which the induction current flows (C part). In Fig. 14, an induction current in a direction opposite to the induction current starts to flow. The induced current flowing in the C portion is defined as the secondary induced current.

On the other hand, when the film thickness of the lower conductor 34 is thin (5 µm), similarly to the thick case, the induced current of the current flowing through the transmission conductor flows to the portion close to the transmission conductor of the lower conductor 34. However, since the lower conductor 34 is thin, when the induced current flows, it flows through the entire surface of the lower conductor 34, and since there is no region where the secondary induced current flows, the secondary induced current does not flow.

Here, the transmission loss generated in the lower conductor 34 is defined as the energy consumed by the lower conductor 34, that is, the power loss generated. Therefore, the sum of the power consumption p in the micro area, which can be calculated by multiplying the square of the current i in the micro area by the resistance r in the micro area, is summed over the volume area of the lower conductor 34. Electric power P becomes.

Therefore, when the secondary induced current flows, power consumption is generated as much as the flow flows. As a result, the time when the secondary induction current starts to flow in the direction of increasing the thickness of the lower conductor 34 becomes the upper limit of the thickness of the lower conductor 34.

On the contrary, when the film thickness of the lower conductor 34 is made thin, the area | region which flows the induced current corresponding to the electric current of a transmission conductor will disappear, and an induced current will not flow. Since induction current does not flow, power consumption decreases, but since sufficient induction current does not flow, the coupling of the high frequency current and induction current of a transmission conductor becomes small. As a result, mutual inductance between transmission conductors becomes small, and the characteristic impedance of a line looks equivalently high. In other words, in the high frequency signal region of the transmission line, a state of bypassing a line having a different characteristic impedance is passed, which may cause transmission distortion. Therefore, power consumption is reduced, but transmission characteristics become poor, which is not preferable as a transmission line. Therefore, the film thickness of the lower conductor 34 when power consumption peaks becomes a lower limit.

Moreover, when the width direction of the induced current of FIG. 14 is enlarged, it is expanded beyond the width | variety of a line conductor. Therefore, when the enlargement range of the width direction is calculated | required from the simulation result, it turns out that the width | variety of half of the space | interval of a conductor and the conductor becomes wide from the conductor end surface. Therefore, it is necessary to make the width of the lower conductor larger than the sum of at least one pair of conductor widths and conductor spacing, and two times the pair of conductor widths is sufficient.

Next, an example of the result of simulating the relationship of the minimum power consumption with respect to the electrical conductivity of the lower conductor which depend on the film thickness of the polyimide resin of an insulating layer is demonstrated using FIG. 15 shows a characteristic diagram of the relationship of the minimum power consumption to the conductivity of the lower conductor.

As shown in FIG. 15, in the example where the film thickness of the polyimide resin of the insulating layer 33 is 5 micrometers, stainless steel (conductivity (sigma) = 1.1E + 06 [S / m]) is made to the lower conductor 34. As shown in FIG. When used, about 110W of power is consumed, while when copper (conductivity σ = 5.8E + 07 [S / m]) is used, about 30W of power is consumed.

Similarly, in the example where the film thickness of the polyimide resin of the insulating layer 33 is 10 micrometers, power consumption can be reduced about 70 W to about 20 W. In the example where the film thickness of the polyimide resin is 18 micrometers, about 10 W to about 45 W The power consumption can be reduced to such an extent.

From the results of the simulations shown in FIGS. 8 to 15 described above, copper is used for the lower conductor 34, so that even though stainless steel having a thickness of 25 µm is conventionally used, copper having a thickness of 5 µm is transferred. The loss can be reduced. Even if the film thickness of copper is set in the range of about 2-12 micrometers from the simulation result, the effect of reducing transmission loss can be expected.

In addition, if the film thickness of the insulating layer 33 that defines the distance between the recording side conductor 30 and the reproduction side conductor 31 and the lower conductor 34 is reduced to 5 to 10 μm from the conventional 10 μm, transmission loss Although this increases, the line becomes thinner, so that the rigidity of the transmission line can be reduced, and it can also be applied to the wiring around the head. In addition, the impedance mismatch in the line around the head can be eliminated, and the transmission band can be expanded.

Therefore, according to the magnetic disk device of this embodiment, the following effects can be obtained.

(1) When the transmission lines 21a and 21b on the suspension 19 have a three-layer structure consisting of the recording side conductor 30, the reproduction side conductor 31, the insulating layer 33, and the lower conductor 34. By using the lower conductor 34 as copper, the power consumption due to the induced current of the lower conductor 34 can be reduced to reduce the transmission loss of the line, and the thickness of the line can be reduced to reduce the rigidity of the head peripheral wiring portion. can do.

(2) The transmission lines 21c and 21d on the suspension 19 consist of the recording side conductor 30 and the reproduction side conductor 31, the insulating layer 33, the lower conductor 34, and the stainless layer 35. In the case of the layer structure, in addition to the effect similar to the above (1), by mounting the stainless layer 35 and the suspension 19 by point welding, it is possible to mount strong and low fluctuations, and the suspension 19 ), Since the stainless layer 35 and the lower conductor 34 can have the same ground, the low frequency noise can be removed.

(3) The transmission lines 21e and 21f on the suspension 19 include the recording side conductor 30 and the reproduction side conductor 31, the insulating layer 33, the lower conductor 34, the insulating layer 36, and stainless steel. In the case of the five-layer structure which consists of the layer 35, in addition to the effect similar to said (1), the stainless layer 35 is provided below the lower conductor 34 through the insulating layer 36, and the stainless layer It is strong by point welding between the 35 and the suspension 19, and can be mounted with low fluctuations, and the lower conductor 34 can be separated from the ground, thereby preventing the mixing of low frequency noise. have.

According to the present invention, the electrical characteristics can be improved by reducing the transmission loss in the transmission line, and the vibration characteristics can be improved by reducing the rigidity of the wiring around the head, thereby improving the electrical characteristics and improving the vibration characteristics. It is possible to realize the flattening of the impedance of the transmission line by making it compatible.

Claims (5)

A magnetic disk apparatus having a magnetic head for recording and reproducing information on a magnetic recording medium, a transmission line for transmitting a recording and reproduction signal between the magnetic head, and a suspension for mounting the transmission line, comprising: The transmission line mounted on the suspension includes a recording side line consisting of a pair of conductors and a reproduction side line consisting of a pair of conductors, Lower conductors are provided in the lower layer of the conductors of the recording side line and the reproduction side line with an insulating layer interposed therebetween. And the lower conductor is made of copper having a thickness of 5 µm or a copper alloy containing copper as a main component. The method of claim 1, The said insulating layer is formed with the polyimide resin of 5-10 micrometers in thickness, The magnetic disk apparatus characterized by the above-mentioned. The method of claim 2, And the lower conductor is electrically at ground potential. The method of claim 3, The lower layer of the lower conductor is provided with a stainless layer, And said stainless layer is formed as a flexure and incorporated with said suspension. The method of claim 3, A lower layer of the lower conductor is provided with a stainless layer with an insulating layer interposed therebetween, And said stainless layer is formed as a flexure and is incorporated with said suspension.

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